Air Pollution and Acid Rain 012-10988 r1.04. Air Pollution and Acid Rain 012-10750 r1.04.

Air Pollution and Acid Rain 012-10988 r1.04

Air Pollution and Acid Rain 012-10750 r1.04

The Snapshot button is used to capture the screen.

The Journal is where snapshots are stored and viewed.

The Share button is used to export or print your journal to turn in your work.

IntroductionJournals and Snapshots

Note: You may want to take asnapshot of the first page ofthis lab as a cover page for your journal.

Each page of this lab that contains the symbol

should be inserted into your journal. After completing a lab page with the snapshot symbol, tap (in the upper right hand corner) to insert the page into your journal.

Air Pollution and Acid Rain

• What is the connection between air pollution and acid rain?

• How does acid rain affect the environment?

Lab ChallengesAir Pollution and Acid Rain

Background• Modern industry can cause a lot of pollution. Coal-burning power plants,

automobiles, furnaces, and factories produce pollutant gases like sulfur dioxide (SO2) and nitrogen oxides (including NO, NO2, and N2O).

• Scientists have discovered that these gas pollutants are the primary causes of acid rain. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds.

• Acid rain causes acidification of lakes and streams and contributes to damage of trees at high elevations and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials (including marble statues), stone, metals like bronze, and automotive paint.


Self-Check1. Acid rain is primarily caused by the

pollutants like nitrogen oxides and...

a) soot

b) carbon dioxide

c) sulfur dioxide

d) pH water

e) elevator music


• Acid rain produces stressful and sometimes deadly fluctuations in water systems causing aquatic life to experience chemical “shock” effects. For example, as the pH drops below 5.5, plankton, certain insects, and crustaceans begin to die and trout eggs do not hatch well.

• Acid rain reduces crop productivity and forest growth rates and accelerates the rate at which metals and nutrients are leached from soils.

• Scientists believe that acid rain can also cause increased concentrations of methylmercury dissolved in waterways. Methylmercury is a neurotoxic molecule that accumulates in fish tissues and can cause birth defects in populations that ingest high concentrations of fish.

...BackgroundAir Pollution and Acid Rain

Self-Check2. Which of the following is LEAST affected by acid

rain?

a) fish eggs

b) trees

c) crustaceans

d) dolphins

e) plankton


• Use all standard laboratory safety procedures.

• Keep water away from sensitive electronic equipment.

• Use goggles and aprons/lab coats.

• Do not touch the HCl used in this lab. Use a pipette to handle HCL.

• In this lab you will create several chemical reactions in an Erlenmeyer flask. Do not remove the rubber stopper from the Erlenmeyer flask once each reaction has started.

SafetyAir Pollution and Acid Rain

Materials and EquipmentCollect all of these materials before beginning the lab.

• pH sensor (1)• Erlenmeyer flask, 50-mL (1)• 1-hole rubber stopper for flask (1)• Glass tubing for rubber stopper (1)• Flexible Teflon tubing to fit glass

tubing, 20 cm (1)• Beaker 40-mL (1)• Graduated pipette & pipetting

bulb• Graduated cylinder, 10- or 100-mL

Materials shared across the class:• Electronic balance

• Sodium bicarbonate (NaHCO3), 5 g• Sodium bisulfite (NaHSO3), 5 g• Sodium nitrite (NaNO2), 1.5 g• 1 M HCl (15-mL)• Water or deionized water, 1 L• Wash bottle containing distilled or

deionized water (1)


A. Repeat gas generation and data collection.

The steps to the left are part of the procedure for this lab activity. They are not in the right order. Write the correct sequence below, then take a snapshot of this page.

Sequencing Challenge

B. Rinse out gas generation bottle, beaker, and tubing.

C. Generate CO2 gas and collect data.

D. Determine changes in pH for each gas.

E. Set up equipment. Open graph display.


1. Connect the pH sensor to your data collection system.

2. Ask your teacher if the pH sensor needs to be calibrated. If so, follow the instructions in blue on the next page. If not, go to step 3.

3. Put 20.0 mL of water into the 40-mL beaker.

4. Rinse the pH electrode with distilled water.

Note: This lab works best when completed by groups of at least two students.

SetupAir Pollution and Acid Rain

To Calibrate the pH Sensor: Note: Only calibrate the sensor if instructed to do so by your teacher.Note: During the calibration process you will not be able to return to this page.

1. Open the Calibrate Sensor screens:a. Tap b. Tap CALIBRATE SENSOR

2. Ensure that the correct measurements are selected:a. Sensor: (name of sensor)

Measurement: pHCalibration Type: 2 point

b. Tap NEXT

3. Calibration Point 1: a. Place the pH probe in a pH 4 buffer

solution. b. Enter 4.0 as the pH in the Standard Value

box under Calibration Point 1. c. Tap Read From Sensor under Calibration

Point 1. d. Rinse the pH probe thoroughly using

distilled water. 4. Calibration Point 2:

a. Repeat the process used in calibration point 1 using a pH 10 buffer solution.

b. Tap OK to exit the calibration screen and then tap OK again to return to the lab.


• sodium bicarbonate (NaHCO3) with hydrochloric acid (HCl) to produce carbon dioxide gas (CO2).

• sodium bisulfite (NaHSO3) with hydrochloric acid (HCl) to produce sulfur dioxide gas (SO2).

• sodium nitrite (NaNO2) with hydrochloric acid (HCl) to produce nitrogen dioxide gas (NO2).

Quick OverviewIn this lab you'll be creating 3 gases: CO2, SO2, and NO2. You will bubble these gases through water to see how they affect pH. You will mix


Q2: If you bubble SO2 gas into water, what will happen to the pH of the water?

Q1: If you bubble CO2

gas into water, what will happen to the pH of the water?

Q3: If you bubble NO2 gas into water, what will happen to the pH of the water?


Procedure: CO2 (g)1. Obtain a sample of powdered sodium bicarbonate (NaHCO3) from your

teacher.

2. Measure out 5 grams of the NaHCO3.

3. Place the NaHCO3 in the Erlenmeyer flask.


Continue to the next page.

Procedure CO2 (g)4. Assemble the flask, stopper, glass tubing or

barbed connector, and flexible tubing, using glycerin around the connections if necessary.

5. At this stage, one group member should hold the pH sensor and free end of the plastic tubing beneath the surface of the water in the beaker and tap the start button to begin collecting data. Another group member should quickly pipette 4 mL of 1.0 M hydrochloric acid (HCl) into the Erlenmeyer flask and immediately stopper the flask.

Use glycerin to lubricate the connection pH sensor

Erlenmeyer flask


Note: If the water in the tubing begins to flow backwards of if the bubbling stops, firmly grasp the Erlenmeyer flask in your hand so that the heat from your hand creates a higher pressure area in the flask. This should expel the gas into the water.

6. Record data for about 200 seconds (until the pH level stops changing and stabilizes), then stop the data set collection.


* To Find the Difference Between Two Data Points:

1. Tap to open the tools palette.

2. Tap and then tap two points on the data run.

3. Adjust using both buttons and then tap .

4. Tap to display the differences.

7. Determine maximum and minimum pH for the CO2 experiment by analyzing its graph (previous page).*

8. Record these max/min values in the adjacent Data Table.


9. Dispose of the contents of the flask and beaker according to your teacher's instructions.

10. Thoroughly rinse the pH sensor electrode using distilled water from the wash bottle.

11. Rinse the beaker, Erlenmeyer flask, and tubing with tap water.

Procedure: CO2 (g)Air Pollution and Acid Rain

Procedure: SO2 (g)1. Measure 5g of sodium bisulfite (NaHSO3).

2. Place the NaHSO3 into the Erlenmeyer flask.

3. Reassemble the flask, stopper, glass tubing or barbed connector, and flexible tubing (same as for CO2 run).

4. At this stage, one group member should hold the pH sensor and free end of the plastic tubing beneath the surface of the water in the beaker and tap the start button to begin collecting data. Another group member should quickly pipette 4 mL of 1.0 M hydrochloric acid (HCl) into the Erlenmeyer flask and immediately stopper the flask.


Note: If the water in the tubing begins to flow backwards of if the bubbling stops, firmly grasp the Erlenmeyer flask in your hand so that the heat from your hand creates a higher pressure area in the flask. This should expel the gas into the water.



6. Determine maximum and minimum pH for the SO2 experiment by analyzing its graph (previous page).*


*To Enter Data into a Table: 1. Tap to open the tool

palette.2. Tap then tap a cell in

the data table to highlight it in yellow.

3. Tap to open the Keyboard screen.


Procedure: SO2 (g)8. Dispose of the contents of the flask and beaker according to

your teacher's instructions.


10.Rinse the beaker, Erlenmeyer flask, and tubing with tap water.


Procedure: NO2 (g)1. Measure 5 g of sodium nitrite (NaNO2).

2. Place the NaNO2 into the Erlenmeyer flask.

3. Reassemble the flask, stopper, glass tubing or barbed connector, and flexible tubing (same as for SO2 run).

4. At this stage, one group member should hold the pH sensor and free end of the plastic tubing beneath the surface of the water in the beaker and tape the start button to begin collecting data. Another group member should quickly pipette 4 mL of 1.0 M hydrochloric acid (HCl) into the Erlenmeyer flask and immediately stopper the flask.


Note: If the water in the tubing begins to flow backwards or if the bubbling stops, firmly grasp the Erlenmeyer flask in your hand so that the heat from your hand creates a higher pressure area in the flask. This should expel the gas into the water.




6. Determine maximum and minimum pH for the NO2 experiment by analyzing its graph (previous page).*


*To Enter Data into a Table: 1. Tap to open the tool

palette.2. Tap then tap a cell in

the data table to highlight it in yellow.

3. Tap to open the Keyboard screen.

Procedure: NO2 (g)8. Dispose of the contents of the flask and beaker according to your

teacher's instructions.


10. Rinse the beaker, Erlenmeyer flask, and tubing with tap water.

11. Store all equipment according to your teacher's instructions.


Data Analysis1. Calculate the change in pH

for each gas experiment. Record in the adjacent table.

2. Snapshot page.3. Save your work

so far.


Analysis1. Were your three predictions about CO2, SO2, and NO2 correct? Did the pH

of the water change as you expected for each gas? Explain below.


Analysis2. Use chemical notation to write a formula for the following reaction:

One molecule of carbon dioxide gas dissolves in water to form one bicarbonate ion and one hydrogen ion.



Two nitrogen dioxide gas molecules dissolve in water to form one nitrate ion, one nitrite ion, and two hydrogen ions.



One sulfur dioxide gas molecule dissolves in water to form one bisulfite ion and one hydrogen ion.


Analysis5. Which gas created the smallest change in pH of the water?


Analysis6. Compare your results with those from other groups. What factors might have

caused some of the variability in change in pH observed?


Analysis7. In the three reactions of gas dissolving in water in this lab, what is the

cause of the reduction of the pH of the water in which these gases are dissolved?


SynthesisUse available resources to help you answer the following questions.

1. Which are considered the primary anthropogenic (man-made) gases that cause acid rain? What are some important sources of these gases?


Synthesis2. Scientists have found that sulfuric acid is the primary acid involved in producing acid

rain.a) What are some of the chemical reactions that produce sulfuric acid in

the atmosphere?

b) Why does radiation from the sun speed up this reaction?


Synthesis3. Coal from states in the western United States, like Montana and Wyoming, has a

lower percentage of sulfur impurities than coal found in the eastern United States. How would the burning of low-sulfur coal change acid rain?


Synthesis4. Discuss the relationship between acid rain and the sulfur and nitrogen cycles.


5. What are some ways to treat the effects of acid rain?

SynthesisAir Pollution and Acid Rain

Synthesis6. What are some ways to prevent the formation of acid rain?


Synthesis7. Although carbonic acid produces only a small decrease in pH of water,

why is it of concern in the environment?


1. Which of the following is true about acid rain?a) It is linked to NOx and SOx molecules in the

atmosphere.b) It can result in the death of many species of

water-dwelling organisms when it causes the pH of lakes systems to move to a range outside their tolerance.

c) Affects soil chemistry and the ability of plant roots to take in nutrients.

d) Increases the mobility of toxic metals in ecosystems.

e) All of the above are true.f) Only A, B, and C are true.


Multiple Choice

Multiple Choice2. Which of the following play important roles in the

formation of acid rain?

a) Solar radiation

b) Buffers in soils and water

c) Water in the atmosphere

d) Nitrogen gas (N2) in the atmosphere

e) Only A and C

f) All of the above


Multiple Choice3. In general, rain exerts harmful effects on

ecosystems when it falls below a pH of ________.

a) 3.5

b) 4.5

c) 5.5

d) 6.5

e) 7.5


Multiple Choice4. Acid rain has been linked to __________.

a) contamination of fish with highly toxic methylmercury

b) damage to fish through reactions that create high aluminum concentrations in the water

c) reduced nutrient uptake by tree roots

d) weakening trees, so they become more susceptible to other types of damage

e) All of the above.


You have completed the lab.Congratulations!

Please remember to follow your teacher's instructions for cleaning-up and submitting your lab.


Images are taken from PASCO documentation, public domain clip art, or Wikimedia Foundation Commons.

http://www.freeclipartnow.com/office/paper-shredder.jpg.html

ReferencesAir Pollution and Acid Rain

Air Pollution and Acid Rain 012-10988 r1.04. Air Pollution and Acid Rain 012-10750 r1.04.

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